I tired to connect the hdmi cable to my tv and it didnt work

Which Linux distro (and version) are you using? You need to provide as much information as possible when posting a question.

What, exactly, do you think we'll be able to tell you from that??? You say nothing about your version/distro of Linux, what kind of hardware, what you're trying to accomplish (main screen? Second screen? Third?), or any message(s) you may have received when doing this. Read the "Question Guidelines" link in my posting signature.

Linux mint 19 cinammon 64 bit

...and now if you could tell us the hardware you're using........

is there a conmmand line to see which hardware im using???

I'm assuming that you're wanting to project your computer/laptop screen onto the HDMI screen (i.e. show a mirror of the screen), given that you have not told us what you are trying to do, despite TB0ne asking you to do so.

If that is the case (I use Mint 19 MATE so I'm hoping that these instructions are correct for Cinnamon):

System Settings->Hardware->Display: Mirror displays

Set sound output to HDMI cable: pactl set-card-profile 0 output:hdmi-stereo.

Reset sound output to PC speakers: pactl set-card-profile 0 output:analog-stereo.

(you can also use pavucontrol->configuration: Digital Stereo (HDMI) Output & Analogue Stereo Output to switch between the two audio outputs but you may have to manually do this once with pactl before using pavucontrol).

rchitecture: x86_64
mode (s) of operation of the CPUs: 32-bit, 64-bit
Byte order: Little Endian
CPU (s): 2
List of the CPU (s) online: 0.1
Processing thread (s) per core: 1
Core (s) by «socket»: 2
«Socket (s)» 1
NUMA mode (s): 1
Manufacturer ID: GenuineIntel
CPU family: 6
Model: 76
Model name: Intel (R) Celeron (R) CPU N3050 @ 1.60GHz
Review: 3
CPU MHz: 2060.545
Max. CPU MHz: 2160,0000
CPU MHz min .: 480,0000
BogoMIPS: 3200.00
Virtualization: VT-x
Cache L1d: 24K
Cache L1i: 32K
Cache L2: 1024K
CPU (s) of node NUMA 0: 0.1
Indicators: fpu vme de pse tsc msr pae mce cx8 apic sep mtrr pge mca cmov pat pse36 clflush dts acpi mmx fxsr sse sse2 ss ht tm pbe syscall nx rdtscp lm constant_tsc arch_perfmon pebs bts rep_good nopl xtopology tsc_reliable nonstop_tsc cpuid aperfmperf tsc_known_freq pni pclmulqdq dtes64 monitor ds_cpl vmx est tm2 ssse3 cx16 xtpr pdcm sse4_1 sse4_2 movbe popcnt tsc_deadline_timer aes rdrand lahf_lm 3dnowprefetch epb pti tpr_shadow vnmi flexpriority ept vpid tsc_adjust smep erms dtherm ida arat

I tried that but my computer odesnt even detect and hdmi connected

Have you tried a different HDMI cable (one that you know works)?

yes

Please connect the HDMI cable to the output device (which is switched on) and paste the output from the command xrandr here.

If you are replying to a specific question, can you please use LQ's "Quote" button so that we know which question you are replying to. Many thanks.

Screen 0: minimum 320 x 200, current 1366 x 768, maximum 8192 x 8192
eDP-1 connected primary 1366x768+0+0 (normal left inverted right x axis y axis) 344mm x 194mm
1366x768 60.00*+ 48.00
1360x768 59.80 59.96
1280x720 60.00 59.99 59.86 59.74
1024x768 60.04 60.00
960x720 60.00
928x696 60.05
896x672 60.01
1024x576 59.95 59.96 59.90 59.82
960x600 59.93 60.00
960x540 59.96 59.99 59.63 59.82
800x600 60.00 60.32 56.25
840x525 60.01 59.88
864x486 59.92 59.57
800x512 60.17
700x525 59.98
800x450 59.95 59.82
640x512 60.02
720x450 59.89
700x450 59.96 59.88
640x480 60.00 59.94
720x405 59.51 58.99
684x384 59.88 59.85
680x384 59.80 59.96
640x400 59.88 59.98
576x432 60.06
640x360 59.86 59.83 59.84 59.32
512x384 60.00
512x288 60.00 59.92
480x270 59.63 59.82
400x300 60.32 56.34
432x243 59.92 59.57
320x240 60.05
360x202 59.51 59.13
320x180 59.84 59.32
DP-1 disconnected (normal left inverted right x axis y axis)
HDMI-1 disconnected (normal left inverted right x axis y axis)
DP-2 disconnected (normal left inverted right x axis y axis)
HDMI-2 disconnected (normal left inverted right x axis y axis)

Can you please paste the output from inxi -G so that we can see which graphics card you are using (there have been known problems with NVidia vis-à-vis the HDMI cable).

Also, can I confirm that the HDMI cable is the only one connected between your computer and the output device in question.